Release Time:2019-03-09  Hits:

Indexed by: Journal Article

Date of Publication: 2014-10-01

Journal: CHINESE JOURNAL OF CHEMISTRY

Included Journals: Scopus、SCIE

Volume: 32

Issue: 10,SI

Page Number: 985-990

ISSN: 1001-604X

Key Words: emulsion catalysis; asymmetric catalysis; organocatalysis

Abstract: A series of of amphiphilic imidazole based secondary and primary amine catalysts were synthesized and shown to be very effective with an acid cocatalyst for the asymmetric reaction of cyclohexanone to ,-unsaturated -keto ester. Interestingly, primary and secondary amine catalysts show different regio-selectivities in this reaction. Under the catalysis of secondary amine 1, excellent enantioselectivities were observed for the products from direct 3+3 reactions of cyclohexanone with ,-unsaturated -keto esters using water as the solvent. Moreover, the same reactants catalyzed by the primary amines 2 lead to the aldol reactions, affording the corresponding products with high diastereoselectivities and up to 97% ee. Theoretical studies on the transition states by using a model in gas phase revealed that steric effect plays an important role on different chemo-selective induction between the secondary amine 1 and primary amine 2.